The present invention relates to linear milling machines and especially to the adaption of such machines for use by divers at substantial underwater depths.
Salvage and other operations conducted by divers require equipment to cut sections of metal panels from submerged structures such as sunken or damaged vessel hulls. Also, in the petroleum industry, there is a rather frequent need to cut out damaged structural portions of pipeline sections although, as far as is known, no successful system has been developed for this purpose. Apparently, the state of the art, at least as far as the salvage operations are concerned, has relied mainly on the use of cutting torches or of linear shaped explosive charges. In some situations, these methods are acceptable although by their nature they are not capable of providing accurate cuts through heavy materials such as submarine hulls or HTS surface ships. Further, both the torches and the explosives pose problems when the vessel contents include dangerously-explosive objects or materials such as torpedoes, ammunition, missiles, etc. Another problem that is conventional torches such as the oxy-arc cutting torches are limited in their underwater use to depths of no more than about 300 feet.
Obviously, there is a need for a cutting machine capable of being carried to the work by the diver and of performing cutting operations entirely under the control of the diver. Milling machines, of course, can perform such cuts although, as is known, conventional machine-shop installations are heavy and cumbersome stationary units on which the work piece is mounted and moved across the cutting head. Such equipment clearly is not suited for underwater work.
The primary object of the invention is to provide an underwater milling machine capable of being transported by a diver to the submerged work piece and of being fully controlled by the diver during its cutting operations.
Another object is to provide a machine which can be secured to the work easily and quickly without the need for heavy bolts or other physical interconnections.
Still another object is to provide a securing arrangement that can be quickly released to enable repositioning of the machine for a continuation cut. As will be described, the securing is achieved by hold-down suction pads.
A further object is to provide an hydraulically-driven milling system which can be pressure-compensated according to the ocean depth and which also can be easily controlled entirely by the diver.
A number of other, more specific objects and advantages will become apparent in the ensuing detailed description.